Salivary Glands Module 2 Flashcards
what are the several common features of acinus aka secretory endpiece?
comprised of a cluster of acinar cells surrounding a central lumen
there are spaces between the cells- intercellular spaces and the cells are joined by tight junctions
end of acinar cell that faces the lumen contains secretory granules
surrounding acinar cells- myoepithelial cell
entire endpiece surrounded by basal lamina
what does the tight junctions and intercellular spaces allow for?
passage of water and small ions but restrict the passage of larger molecules
serous cell characteristics
pyramidal shape
rest on basal lamina
short irregular microvilli- inc surface area
exhibit many characteristics of polarized, protein secreting cells- nucleus toward basal aspect of cell, surrounded by protein synthesizing and processing organelle- rER and golgi apparatus
secrete many enzymes and glycoproteins- packaged in secretory granule in apical part of cell where they are released
what are one class of proteins serous cells do not secrete?
mucins- left to mucous cells
what do ducts have
larger lumen
serous acini lumen-
very small
serous acini nuclei
clear
mucous cell characteristic
more cuboidal to columnar in shape- less pyramidal
oval nuclei pressed toward base
arranged in tubules around a larger central lumen- arranged in acini more elongated and tubular
secrete mucins
mucins cause secretory granules that contain them are pale staining
where are the mucous granules?
in apex of cell- several mucous granules apparently merged together- fixation problem
mucous vs serous appearance
shapes of endpieces more tubular - only seen in longitudinal cross section
cytoplasm of mucous cells much paler staining than serous cell
nuclei of mucous cell- further basally than serous cell
lumen of mucous larger and more obvious
serous demilune
serous cells on top of mucous cells in mixed acinus
due to conventional fixation
rapid freezing technique?
mucous and serous side by side
mucous nuclei not compressed
do not change basic function of mixed acinus
myoepithelial cells-
specialized epithelial cell with contractile properties
surround acini and intercalated ducts
lie within basal lamina
have multiple processes
one cell surround a bunch of multiple cells of acinus
how is myoepithelial cells innervated and what is their function?
neurally innervated
facilitate movement of saliva into ductal system
what does acini open into?
intercalated lead to striated and to excretory- open into oral cavity
does major salivary glands have all three types of ducts?
yes
does minor salivary glands have /all 3 types of ducts
no
intercalated sometimes observed
striated absent
excretory main type
intercalated duct
smallest duct
several acini drain into intercalated duct
ducts short
cells: cuboidal with centrally placed nucleus
function: convey saliva and secrete antimicrobial proteins- lysozyme- break down bacteria- lactoferrin- antiviral fungal and bacterial
lumen larger than acini
striated duct
longer more active duct
site of reabsorption
converts isotonic to hypotonic fluid- primary to secondary saliva
againast conc gradient- requires atp
also site of secretion of proteins and bicarbonate- vital for buffering of saliva
morphology of striated duct
columnar highly polarized short microvilli numerous infoldings o basolateral membrane- striation appearance- large sa for reabsorption prominent mitochondria
pathway for reabsorption
sodium and chloride ions in primary secretions of the lumen get taken up at the apical end of the striated duct cell and transported through the celll to its basal aspect where they pass to capillaries adjacent to the striations at the basal end of the cell
excretory duct
carrying saliva to oral cavity
series of connecting ducts becoming progressively wider closer to mouth
changes in histo of excretory duct?
single epithelial layer to pseudostratified epithelium, sometimes final part of duct becomes stratified and keratinized (increased strength)
excretory duct histo
often located in ct
irregularly shaped lumen
irregularly positioned nuclei- pseudostraitiied. fibroblast surround duct- bc duct often in stroma- ct of the gland where fibroblasts and collagen prominent
what are goblet cells?
intermingled with other excretory duct cells and do secrete mucins
von ebner’s gland
taste bud bearing
foliate and circumvalate papillae of posterior tongue
pure serous
age changes
general loss of parenchyma 30-60%
does not necessarily induce dry mouth- most dry mouth in the elderly drug related
what other diseases and conditions influence salivary gland
mumps- viral, parotid gland swelling
sialoliths- stones, submandibular- obstruct secretion cause painful swelling
mucous plugs or trauma- obstruct secretions from minor glands- painful swelling
several virsuses replicate and shed nto saliva- ebv and herpes
hyposalivation
severity of symptoms dependent on degree of salivary loss xerostomia mucosal changes enamel erosion increases caries difficulty in chewing and swallowing changes in taste
causes of hyposalivation
genetic mutation- rare
medications0 antichlinergic drugs, diuretics, antidepressants, antihistamines, antihypertensives
system disease that give rise to dry mouth
prodromal symptom of mumps- xerostomia, sjogren, diabetes
iatrogenic cause of hyposalivation
head and neck radiotheapy
head and neck radiotherapy
effects rapid and long lasting
initial effect; bc of reduce gland function
later effects- bc of cell death- primarily acinar
newer radiation therapies that more specificially target tumor site can spare salivary function
solution to problem?
use either stem cell therapy or genetically modify remaining tissue to restore salivary flow- transform ductal cells
hyposalivation treatment
preventative- most
frequent dental eval and prophy due to prevalence of complications
artificial saliva- poor patient compliance
salivary stimulants- sugarless candies and chewing gum
drugs- muscarinis cholernergic agonist- trigger salivary flow but gi side effects prohibitive
